02 



Dr= McLachlan on Effective Inductance, Effective 



masses of solid iron from the magnetic circuit, and can be 

 verified by using a solid core or a core of thick strips. 



The effective resistance was also "measured, using cores 

 of 0*38 mm. stalloy and O06 mm. pure iron, of the same 

 dimensions as that supplied with the magneto.. Both cores 



Fig. 13. — Variation of Power factor of primary winding with frequency, 

 'S 0-6 



0-5 



0-4 



^ 0-3 



*h 0-2 



0-1 



5xicr 



!0 15 



Frequency 



20 



per 



25 



second. 



30 



•35x10' 



Armature with brass end-plates ; in housing. 

 Rotor position = after full advance break. 



gave slightly smaller values of the effective resistance than 

 the ordinary core. Stalloy was the best of the three cores, 

 owing to its high resistivity. It may seem peculiar that 

 stalloy 0*38 mm. thick should give a lower effective resist- 

 ance than pure iron of jt the thickness, since a reduction in 

 eddy-current loss would be anticipated. This, however, is 

 due to the fact that for the same ampere-turns or magnetizing 

 force due to the oscillatory current, the flux density, and 

 therefore the loss, is greater with the thinner material. With 

 equal flux, densities the loss in the O06 mm. iron would be 

 less than that in the 0'38 mm. iron. 



